AKT (also known as Protein Kinase B) is a serine/threonine protein kinase that is overexpressed in certain human tumors. Ipatasertib is an AKT inhibitor that is currently being evaluated in clinical trials for the treatment of solid tumors, gastric cancer, and prostate cancer. Ipatasertib is disclosed in, for example, U.S. Pat. No. 8,063,050 (see, e.g., Example 14), as well as International Patent Application Publication No. WO 2008/006040.
(R)-4-(5-methyl-7-oxo-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl) piperazine, or the N-protected derivative thereof, may be used as an intermediate in the synthesis of Ipatasertib. Processes for preparing this intermediate are reported in, for example, International Patent Application Publication No. WO 2013/173736 and International Patent Application Publication No. WO 2013/173768. Scheme 1 of WO 2013/173768 is shown below:

The present disclosure provides improved processes for the large-scale manufacturing of (cyclopentyl[d]pyrimidin-4-yl)piperazine compounds, and more particularly (R)-(5-methyl-7-oxo-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)piperazine, as well as N-protected derivatives thereof. As compared to currently known processes, the processes of the present disclosure advantageously provide improvements in, for example, process conditions, reagent selection, complexity of required unit operations, scalability, and the like.